<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
     <style>
    /* 覆盖；叠加 */

    div {
      color: green;
      font-size: 30px;
    }

    div {
      color: red;
      font-weight: 700;
    }
  </style>
</head>
<body>
     <div>div 标签</div>
</body>
</html>